(1) Improvement of Thermal Detector. Several years ago, we devised a sensitive detector for measuring small temperature changes in nervous tissues associated with their enhanced physiological activities. During the last fiscal year, we have greatly improved the signal-to-noise ratio of our thermal detector. It is now possible to apply our detector to various nervous tissues in which heat production during activity has nerver been detected. (2) Analysis of Sensory Processes in Frog Retina by Taking Heat Production as an Index. Our analysis of physiological events in the dark-adapted frog retina by using our thermal detector was initiated in Martch of 1985. Taking advantage of the improvement of our thermal detector, heat production in the retina induced by brief light stimuli was analyzed in detail. The major portion of our findings is expected to be published in the August issue of Biophysical Journal. (3) New Findings Obtained by Application of Heat Measurement Technique to Frog Spinal Cord. Using isolated bullfrog spinal cord, we succeeded in detecting heat production by the nerve cells in the cord following stimulation of the sensory nerve fibers. The time-resolution and the sensitivity of our thermal detector was high enough to permit a detailed analysis of the source of this heat. Our study of the effects of various pharmacological agents on the process of heat production by the spinal cord is now in progress. (4) Measurement of Mechanical and Optical Changes. By using various techniques developed in this laboratory, small movements and changes in turbidity of various nervous tissues were examined in conjunction with thermal measurements.